A vehicle includes a cluster configured to display driving functions, such as a vehicle speed, an engine speed, a refueling amount, a coolant, and the like and vehicle information.
In addition, the cluster includes further a brake warning lamp, a seat belt warning lamp, an anti-lock brake system (ABS) warning lamp, a traction control system (TCS) warning lamp, and other lamps configured to indicate operation states and warning states of attached systems within the vehicle.
In the cluster of the vehicle, a liquid crystal display (LCD) is mounted to improve display efficiency of various types of information. In addition, various buttons for an audio, a full automatic temperature control (FATC) system, and an emergency lamp are arranged in a center fascia of the vehicle. Here, a lighting device is embedded for visual recognition of a driver when the vehicle is driven at night or in a dark place.
Because the driver should be able to easily and clearly view all information of the vehicle while staring a front sight for safety driving, the vehicle further includes a rheostat switch capable of adjusting brightness of the lighting device.
In lighting adjustment according to this rheostat switch, the brightness of lighting may be adjusted by receiving an input of only a duty variable value at a fixed frequency of the rheostat switch and performing an output to a light-emitting diode (LED) at the same ratio. That is, the rheostat switch adjusts a light reduction amount by control of a duty ratio of an ILL(−) port through a transistor (Tr).
The brightness of the lighting device is adjusted through the adjustment of the rheostat switch and the control of the duty ratio of the ILL(−) port. When ON is made by an ignition key IG+ which is a start switch, a constant voltage of 9V is applied.
On the other hand, an operation mode of the lighting device for the cluster of the vehicle is divided into a daytime mode and a nighttime mode. When a taillight (tail) switch is turned on, primary light reduction (referred to as tail light reduction) to about 80% of brightness in daytime is performed.
Accordingly, there is a problem in that visibility is degraded because the light reduction to a brightness of about 80% as in the nighttime mode is performed in spite of daytime when the driver drives the vehicle while operating the taillight switch in a region which the vehicle is driven in a state in which the light is turned on even in daytime.
In addition, because a determination for light reduction conditions is to be made in parts (for example, an audio, an air conditioner, a switch indicator, and the like) to be controlled in a light reduction scheme for an audio, an FATC system, an LCD, various types of lamps, and the like in current vehicles, there is a problem in that a logic or circuit is not simple compared to functions.